How can I add a building to OSM without the assistance of satellite images?
There’s logs of great tutorials on the Internet that show how to add a building to OSM by tracing its outline from satellite images on openstreetmap.org – but how can I do it without satellite images?
In my case, the satellite images are useless because they’re blurry or there’s a giant cloud in the atmosphere that’s obstructing the view of the ground.
Is there some way for me to, with a GPS-enabled smartphone, literally walk to each corner of the building and tap an “add node” button until I’ve returned to the first node? And then use the corresponding node’s bounded area as the building?
Or is there some way for me to fly a drone on a clear day to take a photo – then somehow overlay that on-top of the OSM data and use that photo (instead of the satellite image) to add draw areas around buildings?
What options do I have to add a building to OSM without satellite imagery?
It depends on where you are mapping. Usually the editors offer a range of different aerial images, and if one is poor, another one may be suitable.
If that is not the case, you can map an estimated building outline with a GPS but this will never be more than an estimation because of the general GPS inaccuracy. If you want to try that you should not add a node at every corner of the building because the building itself will block the satellite signals and cause a very poor result. It works better if you stay away from the building and add a node parallel to every side from some distance (most probably the road). I am mapping new buildings in development areas in this way and after gaining some experience the results are reasonable but it requires lots of time and estimation work.
Drone pics would be a great help but in many countries it is not allowed to operate drones in residential areas, sometimes not even above your own house. So before you buy a drone you should find out about the legal situation in your place.
Whenever I map new buildings by poor arial image or GPS/estimation I always add a fixme tag asking to recheck the outline as soon as better aerial imagery is available.
Doing direct capture of coordinates with a consumer grade GPS is unlikely to give good results. I think if you leave the gps in the same spot the average location might be a little better. There is a GPSBlam plugin for JOSM that tries to do this. For roads and paths the recommendation is normally try to get multiple traces over multiple days.
Some regions may have LIDAR data that’s available for use and can be surprisingly good at seeing through treecover.
This is doable, but with extra steps.
Software like WebODM can be used to process a set of multiple images from drone shots into orthophotos that can then be loaded into JOSM either as geoTIFF or, if you reprocess through QGIS, as mbtiles (both require plugins). You will need your drone to either save GPS positions into the photos or have known Ground Control Points to position what you get. If you just have the former the positional accuracy caveats above also apply, but the relative positions between bits of the image should be better.
Some have also had success using this technique with ground level imagery. My attempts have been … less successful.
P.S. please respect whatever local laws you have WRT drone flights over property especially if it isn’t yours.